胡延明翻譯中期開(kāi)題報(bào)告

畢業(yè)設(shè)計(jì)(論文)外文資料翻譯系 別： 建筑工程系 專(zhuān) 業(yè)： 土木工程 班 級(jí)： B090701 姓 名： 胡延明 學(xué) 號(hào)： B09070111 外文出處： 中國(guó)學(xué)術(shù)前沿期刊網(wǎng) 附 件： 1. 原文； 2. 譯文 2013年01月05日原文：Methods for Progressive Collapse Analysis of BuildingStructures Under Blast and Impact LoadsAbstract： Progressive collapse of building structures under blast and impact loads has attracted great attention all over the worldProgressive collapse analysis is essential for an economic and safe design of building structures against progressive collapse to blast and impact loads. Because of the catastrophic nature of progressive collapse and the potentially high cost of constructing or retrofitting buildings to resist it，it is imperative that the progressive collapse analysis methods be reliable. For engineers their methodology to carry out progressive collapse uation need not only be accurate and concise，but also be easily used and works fastThus，many researchers have been spending lots of effort in developing reliable，efficient and straightforward progressive collapse analysis methods recently. In the present paper，current progressive collapse analysis methods available in the literature are reviewedTheir suitability applicability and reliability are discussedOur recent proposed new method for progressive collapse analysis of reinforced concrete frames under blast loads is also introducedKeywords： progressive collapse analysis；building structures；blast load：impact load Progressive collapse is defined as“the spread of an initial local failure from element to element resulting in the collapse of an entire structure or a disproportionately large part of it”. It refers to the failure of one or a group of key structural loadcarrying members that give rise to a more widespread failure of the surrounding members and partial or complete structural collapseProgressive collapse of building structures might be induced by a series of accidental and intentional events such as false construction order，local failure due to accidental overload，damage of critical component by explosion and earthquakeThis paper only focuses on progressive collapse analysis of building structures induced by abnormal loads，such as blast and impact With the recent progressive collapse of Alfred PMurrah Federal Building and world Trade Center (WTC)researches are more focused than ever on constructing buildings safer from progressive collapse induced by blast and impact loadsProgressive collapse analysis is essential for an economic and safe design of building structures against progressive collapse to blast and impact loadsBecause of the catastrophic nature of progressive collapse and the potentially high cost of constructing or retrofitting buildings to resist it，it is imperative that the progressive collapse analysis methods be reliable For engineers，their methodology to carry out progressive collapse uation need not only to be accurate and concise，but also be easily used and works fastThus，many researchers have been spending lots of effort in developing reliable，efficient and straightforward progressive collapse analysis methods recently The current available methods in analyzing structural progressive collapse could be classified into two major categories，namely the direct simulation method，in which the blast loading effects on structural damage and building collapse are directly simulated，and uncoupled alternative load path method with analysis of the structure by simulating various levels of damage by the removal of key loadcarrying membersIn the present paper，the available progressive collapse analysis methods in the literature are reviewed according to their categoriesBoth advantages and disadvantages of each method are listedTheir suitability，applicability and reliability are also discussedOur recently proposed new method for progressive collapse analysis of reinforced concrete frames under blast 1oads is al so introduced1. Progressive collapse analysis methods for building structures. In this section，the current methods for analyzing structural progressive collapse available in the literature are presented in two major categories，namely the direct simulation method and the alternative load path method1.1 Direct simulation method For the direct simulation method，the building structures，air，and explosive are all modeled in detailExplosion，blast wave propagation and its interaction with structures all need to be simulated，if not，blast and impact loads acting on the building structure should be derived and directly applied to structural componentsThe material nonlinear behavior and dynamic effects and damage due to blast or impact are mostly included in the simulationThis section will list typical applications of direct simulation method in progressive collapse analysis of building structures recently，each with its own characteristic.1.1.1 of building collapse under blast loads Luccioni et al carried out an analysis of structural collapse of an actual building，the AMIA (Israels Mutual Society of Argentina)building，which had suffered a terrorist attack and collapsedIn the analysis，the building was modeled using 3一dimensional solid elements， including the reinforced concrete columns，beams and masonry walls.The analysis of the structural collapse of the building was performed in two stagesThe first part of the analysis consisted of the simulation of the explosion itself from the detonation instant and the second part consisted of the analysis of the effect and interaction with the building of the blast wave generated by the explosionOnly the load produced by the air blast wave was considered in the analysisThe ground motion generated by the explosion was not taken into account Fig2 shows the numerical results of the collapsed buildingThe comparison of numerical results with photographs taken after the terrorist attack showed that the numerical analysis accurately reproduced the collapse of the building under the blast loadThe good agreement between actual damage and that one numerically obtained proves that the detailed simulation of the structure，materials and blast effects are needed for this type of analysis and nowadays represent the only way to successfully run a complete collapse analysis of an entire building This case represents a good example of using direct simulation method to carry out the progressive collapse analysis of structuresThat is，the method could successfully predict the progressive collapse process of the structure under blast and impact loadsHowever，this accuracy is achieved at great costIn order to derive the accurate material parameters，experiments should be carried out firstThe building structures，air，and，explosive should be modeled in detail，which need thousands of elementsSpecial algorithms and software were also needed to calculate the blast wave-structure interaction and to catch the damage and collapse behavior of the building structureTherefore，it is extremely time consuming，and requires a profound knowledge of structural dynamics，damage mechanics，dynamic material properties and computational skills112 Collapse analysis of the World Trade CenterQuan and Brinbaum carried out a 3-dimensiona1 computer simulation of impact and collapse of the WTC North Tower using AUT0DYN 3D computer program to numerically reproduce the entire event of impact and collapse of the North Tower of WTC on September l1.Their model included the entire building of the WTC North Tower and a Boeing 767 passenger jetThe threedimensional finite element model used in the simulation contained a total of 270 000 beam and shell elementsAll the columns on the perimeter wall as well as inside the central core were simplified，being modeled by beam elements instead of using solid elements or shell elementsFloors and roof were modeled by the AUTODYN shell solverThe Boeing 767 airplane was also modeled in detail using AUTODYN shell solver and Lagrange solver. The complete simulation consists of four stages：static equilibrium calculation to get the initial stresses and strains from gravity；simulation of a Boeing 767 airplane impacting the tower；the reduction of the strength and stiffness of the tower resulting from the post-impact fuel fire；and finally，the progressive collapse of the Tower driven by gravityFig4 gives one of the typical results，which presents the material location of the tower at 65 s after the impactAs can be seen，the building had already collapsed to half of its heightThe numerical results showed that a scientifically substantiated plausible scenario for the impact and collapse event of the North Tower could be obtained through the numerical simulationIn the progressive analysis，a reasonable simplification in the modeling such as using simple elements to represent complex behavior of structural members will not affect the accuracy of the results，while this might dramatically reduce the size of the mode1This could save lots of computer memories and computing time，especially for the complex structures，such as tall buildingsOf course， certain finite elements are still needed to be developed.1.1.3 DYN method in progressive analysis of RC flame Hao et ai proposed a DYN method based on the continuum damage mechanics theoryThe main difference between this method and other direct simulation methods is that the explosion initialization and blast wave propagation were not directly modeledInstead， blast loads acting on the structure were calculated firstusing the formulae given in TM51300 and Ref. Then they are directly applied on front，side，roof and rear of the building structure This method was used to analyze structural progressive collapse of a three-storey and two-span reinforced concrete（RC）frame structureComputer software LSDYNA with userdefined subroutines was used to perform the analysesFig5 gives the configuration of the RC frame and the explosive locationIn the analysis，the blast was assumed to be detonated on ground surfaceThe blast weight was chosen to be 1 000kg equivalent of TNT，while the scaled distance used was 17 mkg ，at which only the first floor middle column would collapse due to blast effects The fig shows the numerical results of the structural progressive collapse obtained from DYN method analysisAs can be seen，DYN method gives reasonable prediction of the RC frame collapse under critical blast loadIn their study，comparisons were also made between results from DYN method，GSA and DoD guidelines based alternative load path methodsIt was found both the GSA and DoD based alternative load path methods may not give reliable prediction of structural progressive collapse and usually underestimate the stress and strain response at the supporting joint above the blast damaged columns. As mentioned above，the great improvement of the DYN method is that，interaction between the blast wave and building structure，blast initial and blast wavepropagation are not needed to be directly simulatedIt uses the profound knowledge of blast load distribution to define the blast loads and then directly apply them to the structureThis could dramatically decrease the size of finite element model and increase the efficiency of the simulation To sum up，the direct simulation method can yield reliable predictions of structural collapse to blast and impact loads，but it is extremely time consuming，and requires a profound knowledge of structural dynamics，damage mechanics，dynamic material properties and computational skillsIt is therefore not practical for common engineering applicationThe practicability of this category of methods could be improved in the following way：1)Developing new finite element，which is not only simple to be established and calculated，but also can represent the complex behavior of structural components such as nonlinear and dynamic effects；2)Proposing new method of accurately predicting blast loads around the building structures in different blast scenariosWith the development of computer science，with the improvement of the finite element model and the progress of the load application method，the direct simulation method might become an accurate and efficient way in doing progressive collapse analysis of structural building under blast and impact loads.翻譯：建筑結(jié)構(gòu)在沖擊負(fù)載作用下連續(xù)倒塌分析方法摘要：建筑物在沖擊負(fù)載作用下的連續(xù)倒塌已經(jīng)引起了全世界的極大關(guān)注。對(duì)于一個(gè)經(jīng)濟(jì)的，安全的，能夠抵抗沖擊負(fù)載作用下連續(xù)倒塌的建筑結(jié)構(gòu)設(shè)計(jì)，連續(xù)倒塌分析是必不可少的。因?yàn)檫B續(xù)倒塌的災(zāi)難性特點(diǎn)，和為了抵抗它而潛在的建造和改造建筑物的高額費(fèi)用，所以連續(xù)倒塌分析方法是絕對(duì)必要且可信的。對(duì)于工程師們而言，他們估算連續(xù)倒塌的方法不僅僅要求精確和簡(jiǎn)要，而且容易上手，立竿見(jiàn)影。因而，最近許多研究者都在發(fā)展可靠有效和直接的連續(xù)倒塌分析方法上花費(fèi)了很多的精力。在最近的干物上，當(dāng)前在文獻(xiàn)資料中找得到的關(guān)于連續(xù)倒塌的分析方法被重新審閱。人們廣泛討論它們的適宜性、適用性和可靠性。我們也提出了最近剛剛完成的關(guān)于鋼筋混凝土框架在爆破荷載下的連續(xù)倒塌新分析方法。關(guān)鍵詞：連續(xù)倒塌分析；建筑結(jié)構(gòu)；爆炸荷載；沖擊荷載連續(xù)倒塌被定義為“由于一個(gè)基本的局部構(gòu)件失效在構(gòu)件之間擴(kuò)散最終造成整個(gè)結(jié)構(gòu)或者是不成比例的一大部分倒塌”。其含義為一個(gè)或者一組關(guān)鍵承重構(gòu)件的失效造成周?chē)鷺?gòu)件的失效和部分或者是整個(gè)結(jié)構(gòu)的倒塌。建筑結(jié)構(gòu)的連續(xù)倒塌可能由一系列的意外和人為的因素造成，比如：錯(cuò)誤的建造順序，偶然過(guò)載造成的局部失效，爆炸和地震造成的關(guān)鍵組件的損壞。這篇論文僅僅研究了特殊荷載（如：爆炸和沖擊），造成的建筑結(jié)構(gòu)連續(xù)倒塌的分析。 隨著最近Alfred PMurrah聯(lián)邦大樓和世界貿(mào)易中心（WTC）的倒塌，許多的研究更多的關(guān)注如何建造抵抗由于爆炸和沖擊荷載造成連續(xù)倒塌的建筑。對(duì)于一個(gè)經(jīng)濟(jì)的，安全的，能夠抵抗沖擊負(fù)載作用下連續(xù)倒塌的建筑結(jié)構(gòu)設(shè)計(jì)，連續(xù)倒塌分析是必不可少的。因?yàn)檫B續(xù)倒塌的災(zāi)難性特點(diǎn)，和為了抵抗它而潛在的建造和改造建筑物的高額費(fèi)用，所以連續(xù)倒塌分析方法是絕對(duì)必要且可信的。對(duì)于工程師們而言，他們估算連續(xù)倒塌的方法不僅僅要求精確和簡(jiǎn)要，而且容易上手，立竿見(jiàn)影。因而，最近許多研究者都在發(fā)展可靠有效和直接的連續(xù)倒塌分析方法上花費(fèi)了很多的精力。目前可行的結(jié)構(gòu)連續(xù)倒塌分析方法可以被大致分為兩類(lèi)：直接模擬法，這種方法直接模擬了使結(jié)構(gòu)破壞和建筑物倒塌的爆炸荷載效應(yīng)，和非耦合交替荷載路徑法，這種方法通過(guò)模擬由于移除關(guān)鍵承重構(gòu)件造成的不同水平的損壞來(lái)對(duì)結(jié)構(gòu)進(jìn)行分析。在最近的干物上，當(dāng)前在文獻(xiàn)資料中找得到的關(guān)于連續(xù)倒塌的分析方法被重新審閱。這些文獻(xiàn)既有優(yōu)點(diǎn)又有不足之處。人們廣泛討論它們的適宜性、適用性和可靠性。我們最近也提出了剛剛完成的關(guān)于鋼筋混凝土框架在爆破荷載下的連續(xù)倒塌新的分析方法。1、建筑結(jié)構(gòu)連續(xù)倒塌分析方法在這個(gè)部分，現(xiàn)今在文獻(xiàn)中可以找到的結(jié)構(gòu)連續(xù)倒塌分析方法分為兩類(lèi)，直接模擬法和交替荷載路徑法。1.1 直接模擬法在直接模擬法中，建筑結(jié)構(gòu)，氣流和爆炸都被細(xì)致的建立到模型中去。對(duì)于爆炸產(chǎn)生的沖擊波的傳播方式和其與結(jié)構(gòu)之間的相互作用都需要模擬，或者，需要導(dǎo)出作用在建筑結(jié)構(gòu)上的爆炸和沖擊荷載并使它們直接作用在結(jié)構(gòu)構(gòu)件上。大多數(shù)爆炸和沖擊造成的材料非線性反應(yīng)和動(dòng)力效應(yīng)還有損壞都被包括在這種模擬當(dāng)中。在這個(gè)部分，我們會(huì)列出直接模擬法在建筑結(jié)構(gòu)連續(xù)倒塌分析方法中的幾種典型的應(yīng)用，每種都有各自的特點(diǎn)。1.1.1 爆炸荷載下的建筑倒塌的直接模擬 Luccioni et al 曾經(jīng)對(duì)一座真實(shí)的建筑物進(jìn)行了結(jié)構(gòu)倒塌分析。這座建筑叫做“AMIA”，屬于阿根廷猶太人互濟(jì)會(huì)，被恐怖分子襲擊并倒塌。在這項(xiàng)分析當(dāng)中，用3維固體構(gòu)件（包括鋼筋混凝土柱，梁和砌體墻）組裝成這座建筑物的模型。 這座建筑的結(jié)構(gòu)倒塌分析分為兩個(gè)階段。分析的第一個(gè)階段，包括模擬即時(shí)引爆的爆炸本身。第二階段包括建筑與爆炸產(chǎn)生的沖擊波之間的效應(yīng)和相互作用。分析考慮了沖擊波激起的氣流產(chǎn)生的唯一的荷載。爆炸所產(chǎn)生的地面運(yùn)動(dòng)，沒(méi)有考慮。倒塌的建筑物的數(shù)值結(jié)果如圖2所示。數(shù)值結(jié)果和恐怖襲擊之后拍攝的照片比較可以看出：數(shù)值分析準(zhǔn)確的重現(xiàn)了在爆炸荷載作用下建筑的倒塌過(guò)程。實(shí)際損壞和數(shù)值模擬的結(jié)果的很好的一致性，證明了細(xì)致化的結(jié)構(gòu)、材料和爆炸效應(yīng)模擬對(duì)于這種分析是必需的，并且是現(xiàn)今唯一能夠成功的進(jìn)行的對(duì)整個(gè)建筑的完整倒塌分析的方式。這是利用直接模擬方法分析結(jié)構(gòu)連續(xù)倒塌的一個(gè)很好的例子。這種方法能夠成功的預(yù)測(cè)由于爆炸和沖擊荷載造成的連續(xù)倒塌的過(guò)程?？墒?，要達(dá)到這種準(zhǔn)確度是要花費(fèi)很大的代價(jià)的。為了導(dǎo)出準(zhǔn)確的材料參數(shù)，需要先做很多的實(shí)驗(yàn)。建筑結(jié)構(gòu)、空